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Scientists have found 10 to 20 new species of tiny creatures in the depths of the Atlantic, says an international report.

The survey, of tropical waters between the eastern US and the mid-Atlantic ridge, used special nets to catch thousands of species of fragile zooplankton.

New finds included six types of ostracods, a shrimp-like creature, and other species of zooplankton such as swimming snails and worms.

Zooplankton are mostly millimeters long but range up to jellyfish trailing long tails.

They live at lightless depths of 1 to 5 kilometres and are swept by ocean currents.

"This was a voyage of exploration ... the deepest parts of the oceans are hardly ever sampled," says Dr Peter Wiebe, the cruise's scientific leader and senior scientist at the Woods Hole Oceanographic Institution in the US.

"We found perhaps 10-20 new species of zooplankton," he says of the voyage by 28 scientists from 14 nations, including Australia, in April.

The scientists also found new fish.

Among 120 types of fish caught, the scientists found what may be a new type of black dragonfish, with fang-like teeth, growing up to about 40 centimetres, and a 20-centimetre-long great swallower, with wide jaws and a light-producing organ to attract prey.

Most life, including commercial fish stocks, is in the top 1 kilometre of water, but the scientists say the survey shows a surprising abundance even in the depths.

The survey will provide a benchmark to judge future changes to the oceans, the scientists say.

"By 2010, the research ... will provide a baseline against which future generations can measure changes to the zooplankton and their provinces, caused by pollution, over-fishing, climate change, and other shifting environmental conditions," says Professor Ann Bucklin, lead scientist for the zooplankton census project at the University of Connecticut.